Infrared Detectors and Emitters: Materials and Devices

Infrared (IR) detectors fall into two main categories, thermal and photon. The earliest detectors of IR were thermal in nature, e.g. thermometers. The subsequent developments of these detectors, such as thermopiles, resistance bolometers, Golay cells and pyroelectric detectors, can operate at ambient temperature but have disadvantages of insensitivity and slowness. A wide variety of semiconductor photon detectors have been developed and these possess very high sensitivity, high frequency response but have the disadvantage of needing cryogenic cooling, particularly at longer wavelengths. In the main, the applications have been in the military sphere, but widespread industrial and scientific applications also exist. The majority of development funding for these semiconducting IR detectors has, however, come from military sources. This book is an attempt to provide an up-to-date view of the various IR detector/emitter materials systems currently in use or being actively researched. The book is aimed at newcomers to the field and at those already working in the IR industry. It is hoped that the former will find the book readable both as an introductory text and as a useful guide to the literature. Workers in one of the various IR areas will, hopefully, find the book useful in bringing them up-to-date with other, sometimes competing, technologies. To both groups of readers we trust that the book will prove interesting, thought-provoking and a spur to further progress in this fascinating and challenging field of endeavour.

Table of Contents:
1 Introduction to Infrared Devices and Fundamentals of their Operation.- 1.1 Introduction.- 1.2 Types of IR detector.- 1.3 Emitters.- References.- 2 Assessment of Infrared Materials and Devices.- 2.1 Introduction.- 2.2 Material Characterization.- 2.3 Device Characterization.- 2.4 Detector Comparisons.- 2.5 Emitter Comparisons.- References.- 3 IV-VI (Lead Chalcogenide) Infrared Sensors and Lasers.- 3.1 Introduction.- 3.2 Some Material Properties.- 3.3 Growth Techniques.- 3.4 Infrared Sensors.- 3.5 Lead Salt Infrared Emitters.- References.- 4 Metal Silicide Schottky Infrared Detector Arrays.- 4.1 Introduction.- 4.2 Internal Photoemission.- 4.3 Silicon Substrate.- 4.4 Platinum Silicide.- 4.5 Cut-off Extension.- 4.6 Pixel Design.- 4.7 PtSi SB FPAs.- 4.8 Summary.- References.- 5 Pyroelectric Materials and Devices.- 5.1 Introduction.- 5.2 The Physics of Pyroelectric Detectors.- 5.3 Pyroelectric Materials and Their Selection.- 5.4 Pyroelectric Thermal Imaging.- 5.5 Pyroelectric Arrays, Design, Technology and Performance.- References.- 6 Uncooled Microbolometer Infrared Sensor Arrays.- 6.1 Introduction.- 6.2 Fabrication of Arrays of Thermal Sensors.- 6.3 Micromachined Microbolometer Design and Fabrication.- 6.4 Temperature-Sensitive Resistor Materials for Microbolometers.- 6.5 Microbolometer Micromachining Sequence.- 6.6 Typical Microbolometer Parameters.- 6.7 Thermal Isolation of Microbolometers.- 6.8 Infrared Absorption in Microbolometers.- 6.9 Readout of Two-dimensional Arrays of Microbolometers.- 6.10 Calculation of the Performance of Bolometer Arrays.- 6.11 Practical Infrared Cameras Using Microbolometer Array.- 6.12 Conclusion.- Acknowledgments.- References.- 7 InSb: Materials and Devices.- 7.1 InSb: the New-Old IR Material.- 7.2 InSb is Different.- 7.3 Purification and Doping.- 7.4 Crystal Growth.- 7.5 Fabrication.- 7.6 Finishing.- 7.7 Useful Techniques.- 7.8 InSb Devices.- References.- 8 Growth, Properties and Infrared Device Characteristics of Strained InAsSb-Based Materials.- 8.1 Introduction.- 8.2 Growth and Characterization of InAsSb by Metal-Organic Chemical Vapor Deposition (MOCVD).- 8.3 Infrared Device Results.- 8.4 Summary and Future Directions.- Acknowledgments.- References.- 9 Tl-Based III-V Alloy Semiconductors.- 9.1 Introduction.- 9.2 Expected Properties of Tl-Based III-V Alloys.- 9.3 Growth Issues.- 9.4 TlInSb on InSb.- 9.5 TuInAs on InAs.- 9.6 T1InP on InP.- 9.7 T1GaP on GaAs.- 9.8 T1GaAs on GaAs.- 9.9 T1InGaP on InP.- 9.10 TlInGaAs on InP.- 9.11 Summary.- References.- 10 MCT Materials Aspects.- 10.1 Introduction.- 10.2 Bulk Growth Techniques.- 10.3 Liquid Phase Epitaxy (LPE).- 10.4 Metal-Organic Vapor Phase Epitaxy (MOVPE).- 10.5 Molecular Beam Epitaxy (MBE).- References.- 11 Photoconductive and Non-equilibrium Devices in HgCdTe and Related Alloys.- 11.1 Introduction.- 11.2 Photoconductive Detectors.- 11.3 Non-equilibrium Devices.- 11.4 Conclusions.- Further Reading.- References.- 12 Photovoltaic Detectors in MCT.- 12.1 Introduction.- 12.2 Historical Perspective on Photovoltaic Detectors in MCT.- 12.3 MCT Hybrid Focal Plane Array Configurations.- 12.4 Principles of Operation and Figures of Merit for MCT PV Detectors.- 12.5 Junction Current Mechanisms for MCT Photodiodes.- 12.6 MCT Junction Photodiode Architectures.- 12.7 Recent Advances in SW and MW MCT Photodiodes.- 12.8 Recent Advances in VLW MCT Photodiodes.- 12.9 Dual-Band MCT Detector Arrays.- 12.10 Summary, Conclusions and Trends.- Acknowledgments.- References.- Appendix A: Guide to the HgCdTe Literature.- 13 Hg-Based Alternatives to MCT.- 13.1 Introduction.- 13.2Crystal Growth.- 13.3 Some Physical Properties.- 13.4 HgZnTe Detectors.- 13.5 HgMnTe Detectors.- 13.6 Conclusions.- References.- 14 Reduced-Dimensionality HgTe-CdTe for the Infrared.- 14.1 Introduction.- 14.2 Energy Bands and Effective Masses.- 14.3 MBE Growth.- 14.4 Absorption, Lifetime, and IR Detectors.- 14.5 Photoluminescence.- 14.6 IR Lasers.- 14.7 Summary.- References.- 15 Quantum Well Infra-red Detectors.- 15.1 Introduction.- 15.2 The QWIP as a Photoconductive Detector.- 15.3 The Microscopic Physics of the QWIP.- 15.4 Performance of AlGaAs/GaAs QWIPs.- 15.5 Optical Coupling Methods.- 15.6 Imaging Arrays.- 15.7 QWIPs in materials other than n-type AlGaAs/GaAs.- 15.8 Conclusions and Future Prospects.- References.